Timed flow control method and apparatus



Oct. 26, 1965 R. o. WALTON TIMED FLOW CONTROL METHOD AND APPARATUS 4 Sheets-Sheet 1 Filed Sept. 5, 1963 INVENTOR. Fads/*2 0. Wa/zon BYg Oct. 26, 1965 R. o. WALTON TIMED FLOW CONTROL METHOD AND APPARATUS 4 Sheets-Sheet 2 Filed Sept. 5, 1963 ATTORNEY Oct. 26, 1965 R. o. WALTON TIMED FLOW CONTROL METHOD AND APPARATUS 4 Sheets-Sheet 3 Filed Sept. 5, 1963 INVENTOR.

WOW/ ATTOP/VE V M M Z 11 My? /0B 0 Oct. 26, 1965 R. o. WALTON TIMED FLOW CONTROL METHOD AND APPARATUS Filed Sept. 3, 1965 4 Sheets-Sheet 4 V r v 1 h INVENTOR. F04; er I 0. Wa/zofi ATTORNEY United States Patent Ofi ice 3,213,896 Patented Oct. 26, 1965 3,213,806 TIMED FLOW CONTROL METHOD AND APPARATUS Robert 0. Walton, Odessa, Tex., assignor to Merla Tool Corporation, Garland, Tex., a corporation of Texas Filed Sept. 3, 1963, Ser. No. 305,921 15 Claims. (Cl. 103232) This invention relates to flow control means for well fluids and consists particularly in novel means for controlling the flow of a fluid, such as lifting gas, from the annulus into the production tubing of an oil well.

Presently known types of gas lift systems involve the application of flow control devices at intervals along the production tubing for admitting pressured lifting gas from the well annulus into the column of liquid in the tubing. Such devices may respond, primarily, to the liquid head within the tubing, or the annulus gas pressure, or the differential between the two for opening a flow valve in the tubing wall. All of such systems are unsatisfactory under some operating conditions. For instance, the flow valves may not perform properly in a multiple string well where the pressures in the different tubing strings may vary widely. Since the annulus pressure must exceed the highest static pressure in a tubing which is to be subjected to gas lift, once a flow valve in a tubing string at lower pressure is opened, the pressure therein may remain so high, even after the liquid column has been greatly reduced, that the flow valve cannot close. Furthermore, even in a single string well, a fairly accurate control of the gas pressure and the timing of intermittent annulus pressuring means must be maintained. Thus, if such control is not maintained, for instance, where an attendant has many wells to watch, gas may be wasted or a well may become blocked due to excessive buildup of a liquid column. Frequently, an attendant may err on the safe side with resultant wastage, in an eifort to insure continued flow of all of the wells under his supervision, for instance, by providing for too frequent intermitting of the gas supply.

Accordingly, an object of the present invention is to provide a novel flow control system in which the flow valve is positively closed after a predetermined time interval, irrespective of tubing or annulus pressure.

Another object is to provide such a control in which the flow valve can open only when .at least a predetermined pressure exists in the tubing and which will close automatically after a predetermined time interval.

Another object is to provide a gas lift system which requires a minimum of attention.

In accordance with an exemplary embodiment of the invention as here disclosed, there is provided in a tubing string one or more flow valves having operating means which respond to the head of liquid in the tubing adjacent a particular valve for initially opening the same to admit lifting gas from the well annulus. coincidentally therewith, timing mechanism is set in motion for automatically reclosing the valve after a predetermined time interval, for maintaining the valve closed during a measured period and, thereafter, reopening the valve provided the liquid in the tubing in the vicinity of the valve remains at the critical pressure. The fiow valve and its control may be mounted as a unit on the tubing wall, or a separate, timed actuator may be provided which may be run into the well for cooperation with flow valves previously inserted in the tubing string, as described in my co-pending application Serial No. 306,192 filed September 3, 1963.

In the accompanying drawings which illustrate the in- 'vention,

FIG. 1 is a largely schematic sectional representation of an oil well having a production tubing string with the invention applied thereto;

strength and chemical properties.

FIG. 2 is an enlarged vertical transverse center section through the flow valve and control device in operative condition;

FIG. 3 is a similar view showing the flow valve closed by the action of the timing mechanism;

" FIG. 4 is a similar view showing the flow valve remaining closed and the actuator fingers retracted due to insufiicient tubing head pressure;

FIGS. 5 and 6 are vertical transverse center sections through a modified form of the invention, showing the flow valve, respectively, in closed and opened position;

FIG. 7 is a view of a portion of the structure in FIG. 5 utilized as a pilot valve;

FIG. 8 is an enlarged sectional detail showing the pilot valve arrangement in FIGS. 14, inclusive;

FIG. 9 is a horizontal section taken on line 99 of FIG. 3 and also showing the pilot valve arrangement;

FIG. 10 is an enlarged sectional view showing position of the actuator control, as in FIG. 2.

FIGURE 1 shows an oil well casing 10 extending from a casing head 11 at the surface 12 of the ground downwardly through the earth to a producing formation 13. A tubing string 14 extends through the casing and the annulus 15 is packed off at 16 just above formation 13. Production perforations 17 and a foot valve 18 are provided at the lower extremity of the tubing string. At its upper extremity, the tubing string connects with piping 19 leading to a separator or other treating and storage equipment, while a pipe 20 communicates with the top of annulus 15, as for supplying lifting gas thereto. One or more annular flow valve devices 21 are inserted in the tub ing string when it is run. Within the tubing string there is provided an actuator device, generally designated 22.

FIGURES 2, 3 and 4 illustrate the flow valve and actuator devices in detail. The flow valve is contained within a tubular, somewhat enlarged housing 25 having pin and box joints 26 and 27 at its extremities for insertion in the tubing string in alignment therewith. An annular space 28 is provided in the housing between walls 29 and 30 thereof. In this space there is mounted a sleeve-type check valve 31 of elastomeric material having suitable The sleeve valve has feathered lower and upper ends 32 and 33 secured, respectively, to the opposing walls 29 and 30 of space 28 so as to divide the same into lower and upper chambers 34 and 35. Upper chamber 35 communicates with the well annulus 15 through ports 36 and with the interior of the housing through ports 37. A resiliently expansible and contractible coiled spring 38 is received about the sleeve valve and normally urges the center thereof against inner wall 29 in a manner to close ports 37 and prevent the flow of annulus fluid therethrough.

Main flow valve 31 is a slave valve and is actuated by a pilot valve best illustrated in FIGS. 8 and 9. The inner wall of housing 25 is provided beneath chamber 34 with an annular recess 39 which communicates through a radial passageway 40, an enlarged valve chamber 41, and a port 42 with the well annulus. Valve chamber 41 is connected by a passage 43 with lower flow valve chamber 34. A ball type pilot valve 44 is loosely received in chamber 41 and has a stem 45 which projects through passage 40 and has an actuating head 46 at its inner extremity. Head 46 is urged by a coiled spring 47 against a semi-circular pilot actuating member 48 which is pivotally mounted .at 49 within recess 39. Member 48 is in position to be radially shifted by actuating fingers 50 for moving the pilot valve, as will be explained.

The actuator device includes an upper hollow body part formed of threadedly assembled cup members 52 and 53 and a lower tubular body structure formed of threadedly assembled parts 54, 55, 56 and 57. The actuator device is of such shape and size externally as to permit the .66 in body members 52 and 53. A fishing head 67 is ,provided at the upper extremity of stem 63 for manipulation thereof from a wire line, if desired. A fixed orifice 68 extends through plunger 62. Also extending through this plunger is a passageway 69 having an enlarged central portion 70 forming a valve chamber for a check ball 71 arranged to seat on downward movement of cylinder 61. The check opens on upward movement of the cylinder to permit the transfer of fluid across the plunger through passage 69 as well as passage 68. A

'coiled compression spring 72 is received about stem 64 between plunger 62 and the lower end of body member 53. The lower extremity 73 of body member 53 is tapered for a purpose to be described.

Stem 64 depending from plunger 62 and its abutting extension 64a extend entirely through and are slidable within an axial passageway in the lower body structure of the actuator device. This passageway is enlarged in body members 54 and 56 to form chambers 75 and 76 within which are received fluid charged bellows or capsules 77 and 78 (FIG. An orifice 79 connects the interior of housing 25 and the tubing string with chamber 75 and the exterior of bellows 77. The interiors of bellows 77 and 78 are connected by axial and crosspassages 80 and 81, valve chamber 82, and ports 83 in stem 64. A check ball 84 normally seats upwardly against the lower end of axial passage 80. During downward movement of stem 64, fluid may pass downwardly from bellows 77 past ball 84 into bellows 78.

Chamber 76 beneath bellows 78 merges with four equally spaced slots 86 (-FIG. 9) through which projects actuating fingers 50 which overlap pilot valve actuator half ring 48. At its lower end, stem 64a projects into a chamber 90 in bottom body part 57 which communicates with interior of main housing 25 through orifices 91. Within chamber 90 there is mounted a fluid charged bellows 92 the movable upper wall of which is secured to stem 64a. The bottom wall of part 57 is provided with a bellows filling orifice and valve 93. Actuator fingers 50 are pivotallly secured to stem 64 by means of pins 94. A pair of pins 95 traverse chamber 76 just beneath fingers 50 for camming the fingers outwardly to pilot valve actuating position when stem 64 is lowered. Stem 64 is constantly urged downwardly by a coiled spring 7 8a within bellows 78.

The portion of stem 64 abreast the upper part of body part 54 is provided with an L-shaped slot 97. A generally fish-hook shaped resilient latching element 98 is received in this slot with its lower end lodged between a pin 99 and the adjacent longitudinal wall of the slot. In its normal latching position (FIG. 3) the shoulder 100 of the latching element overlies the upper surface 191 of body part 54 to secure stem 64 in its upper position. In this position of the stem, pilot actuating fingers 50 will be retracted within radial slots 86 so as to clear pilot actuating half ring 48. With actuator fingers so retracted, the entire actuator device can be run through the tubing, including housing 25 without opening the pilot valve. The top of slot 9-7 is formed by a V-section un latching recess 102.

Body part 54 of the actuator device may be equipped with anchoring lugs 105 urged radially outwardly by coiled compression springs 106 so that these lugs, bearing resiliently against the inner wall of housing 25, serve to hold the actuator device in its set position. Where these lugs are used, it may be necessary to install the actuator device in the tubing string at the surface. However, the actuator device may be recoverd by wire line without removing the tubing. Intermediate body part 55 is of generally H-section and includes the fixed orifice restriction 107 which connects bellows or capsules 77 and 78.

The form of the invention just described operates as follows:

As indicated in FIG. 1, the pipe string will be run with flow valve devices 21 incorporated therein at desired intervals and one or more of the actuator devices 22 may be positioned abreast of the flow valves. The pressure responsive capsule 92 in each actuator device will be properly set at the surface to prevent expansion of the actuator fingers 50 until an adequate head of liquid is accumulated above the associated flow valve. Hydraulic charges will be provided in cylinder 61 and in connected capsules 77 and 78 and orifices 68 and 69 in plunger 62, and 81 in stem 64, and 107 in H-shaped body member 55 will be adjusted at the surface to provide for the desired timed operation of the actuator device by dash pot action. While stem 64 is provided at its upper extremity with a retriever lug 67, permitting control of the actuator from the surface, if desired, the actuator device is designed for full sub-surface control. The flow valves are normally closed and the pilot actuating elements 48, normally, are in position within their associated annular recesses 39 in housings 25 so as to ofler no obstruction to a tool being run through the easing, including the actuator devices themselves, provided actuator fingers 50 are retracted.

With reference to a particular actuator device lodged in operative relationship with respect to one of the flow valves, as long as there is insufiicient head of liquid within the tubing above the flow valve and actuator device to contract charged capsule 92 at the bottom end of stem 64a, stem 64 will be elevated against spring 78a to maintain fingers 50 retracted or collapsed and latch spring 98 will be in its latching position, as shown in FIG. 3. Plunger forming upper body 52, 53, normally, will be held by spring 72 in its lower position resting against upper surface 101 of the lower body structure. In this position, V-section recess 102 in stem 64 will have engaged and distorted latching spring 98 to its unlatched position, as shown in FIGS. 2, 4 and 10.

Now, when the liquid pressure head above the actuator increases sufficiently to compress capsule 92, stem 64a will be drawn downwardly and sem 64 will follow expanding actuator fingers 50 to their pilot valve actuating positions, as in FIGS. 2 and 10 wherein the fingers will cause outward pivoting of actuator half ring 48 so as to shift stem 45 and pilot valve 44 rightwardly. This will cause the pilot valve to move from its seating position against the end of on'fice 40 to seat against orifice 42 and thereby cut off communication between annulus 15 and lower flow valve chamber 34 while connecting this chamber through passage 43 with the interior of housing 25 and the tubing string. Since the annulus gas pressure continues to be applied through orifices 36 to upper flow valve chamber 35 and the upper surface of flexible sleeve valve 31, if adequate gas pressure is maintained in the annulus and tubing head sensitive capsule 92 is properly charged, the tubing pressure now applied to the undersurface of flow valve 31 will be less than the annulus pressure so that flow valve 31 will be flexed away from inner orifices 37 as in FIG. 2, thus admitting lifting gas to the interior of housing 25 and the tubing string. This gas will increase the pressure within the housing below upper element 52 of the plunger forming upper body and will lift the entire upper body, against spring 72, as shown in FIG. 3. At the same time, gas will escape through the clearance around plunger part 32 and will ascend in the tubing, carrying with it a slug of liquid and/ or aerating liquid in the tubing in the known manner. The time required for full lifting of body-plunger 52, 53 will be determined by the size of orifices 68 and 69 in a fixed plunger 62, check valve 71 being opened during this period, the plunger 62 and chamber 61, thus, forming a dash pot.

At the upper end of the plunger stroke, spring 72 will be compacted so as to urge plunge-r 62 and stem 63, 64 upwardly sufficiently to retract pilot actuating fingers 50, as shown in FIG. 3, whereupon flow valve 31 recloses. During upward stem movement, the transfer of liquid charge from lower capsule 78 to upper capsule 77 will be limited to orifice 107, check ball 84 being closed at this time, delaying the contraction of fingers 48 and the resultant closing of the flow valve long enough to permit the full stroke of plunger part 52, 53. When the pilot valve is re'seated against inner orifice 40, annulus gas pressure is again admitted to lower flow valve chamber 34 resulting in equalization of pressures across the flow valve. Spring 38 closes the sleeve valve against orifices 37 and the supply of lifting gas is discontinued. Thereupon, the pressure beneath plunger body member 52 drops, permitting the plunger to be urged downwardly by spring 72. During the descent of the plunger body, the transfer of liquid across plunger 62 is restricted to orifice 68, check valve 71 being closed. Thus, return of the plunger body requires a predetermined measured time interval during which latch 98 insures that the gas flow valve remains closed. At the end of this interval V slot 102 in stem 64 again contacts latch spring 98 and distorts it to the unlatched position. If at such time, the head pressure in housing 25 is insufficient to compress capsule 92, stem 64 remains in its upper position (FIG. 4) and actuator fingers 50 remain collapsed so that lifting gas is not admitted. If and when the head pressure again increases sufficiently to compress bellows 92, actuator fingers 50 will again expand and the flow valve will be reopened to repeat the cycle. If gas cycling through a particular flow valve is unsatisfactory for any reason the actuator device may be readily retrieved and reset and/ or repositioned, as required.

The principle of the invention may be incorporated in an arrangement as shown in FIGS. 5, 6 and 7, in which the combined flow valve and control devices are permanently incorporated in a tubing string section. According to this form of invention, each such device comprises a generally tubular housing part 112, secured as by means of a welded lug 114 at the bottom to a tubular part 113 inserted in the tubing string and intermediately secured to the tubing string by welded boss structure 115. Housing 112 has intermediate transverse bafiles 116 and 117, provided with restricted orifices 118 and 119, and also annular ledge structures 120 and 121 which, respectively, loosely receive stems 122 and 123. At the upper end of housing 112 there is provided an accumulator chamber 125 having a filling orifice 126 at its upper extremity, normally closed by a plug 127.

Beneath partition 116 there is provided a second chamber 128 within which there is mounted a bellows or capsule 129 sealingly secured at its upper end to baflle 116 and secured at its lower end to the head 130 of stem or plunger 122 which depends through orificed ledge 120 into a third chamber 131, 135. Second chamber 128 communicates through a port 132 in boss structure 115 with the interior of the tubing string. Slidable in chamber 131, 135 is a sealed piston 133 which is constantly urged downwardly by a coiled compression spring 134. The chamber portion 135 beneath piston 133 is connected through restricted orifice 119 in partition 117 to a fourth chamber 136, 139 in which slidably works a sealed plunger element 137. Baffle 117 is also provided with a check valve controlled orifice 138, the check valve seating upwardly.

Formed as a rigid part of plunger element 137 and depending into a chamber portion 139 is a cage member 140 in which is slidably received the head portion 141 of previously mentioned stern element 123 which extends loosely through an orifice 142 in the bottom wall of the cage member and also through an orifice in guide ledge element 121. Stem 123 is enlarged at its lower extremity to form a valve 143 which control-s a passageway 144 leading from valve chamber 145 at the bottom of the housing 112 into the interior of the tubing string. Valve chamber 145 communicates through ports 146 with the annulus between the tubing string and easing. A short coiled spring 147 is received about stem 123 and rests upon the bottom wall of cage 140. A somewhat similar, short coiled spring 148 rests upon head 141. An over center latch spring element 149 is secured to the side of stem 123. This latch spring normally projects outwardly, as shown in FIGS. 5 and 6, but may be compressed within a slot 150 in the stem to permit the spring to pass guide ledge 121.

In operation of this form of the invention, flow valve devices as described will be run into the well properly positioned on the tubing to be affected. Capsule 129 and chamber portions and 136 on opposite sides of partition 117 will be partially filled with suitable fiuids. The pressure of annulus fluid is at all times applied through orifices 146 and past valve stem 123 into chamber portion 139 and thence to the undersurfaces of cage member and plunger 137. If the annulus pressure, for instance, the pressure of lifting gas in the annulus is sufficiently greater than the tubing head pres-sure prevailing in chamber portion 131, the cage and plungers 137 and 133 will be forced upwardly to the position of FIG. 6, the fluid charge in chamber portion 136 being forced through orifices 119 and 138 into chamber portion 135 to lift plunger 133. If capsule 129 is in its extended position, as in FIG. 5, stem 122 depending therefrom will serve as a stop, limiting the movement of plungers 133 and 137 so that cage member 146 cannot rise far enough to actuate valve stem 123. However, if the tubing head pressure applied through orifice 132 is sufiicient to collapse bellows 129, as in FIG. 6, plungers 133 and 137 can rise far enough to permit the lower wall of cage member 140 to contact and compress short coiled spring 147. The compression of valve opening spring 147 ultimately will cause over center spring 149 to snap past guide ledge 121 to move valve stem 123 upwardly and thereby open valve 143, permitting annulus fluid to enter chamber through ports 146 and thence to pass through passageway 144 into the interior of the tubing string. At the same time, coiled spring 134 will be compressed between piston 133 and ledge 120.

Upon opening of valve 143, cage member 140 and the under surface of plunger 137 will be exposed to tubing pressure. Since the pressures against lower and upper plungers 137 and 133 will be substantially equalized, return spring 134 will expand, forcing the plungers downwardly. Ultimately, valve closing spring 148 will be compressed between stem head 141 and the top wall of cage 140 forcing stem 123 to snap past guide ledge 121, again closing valve 143. During downward movement of the plunger system, check valve 138 will open. Thus, as in the previous form, opening of the flow valve can occur only when the tubing pressure reaches a predetermined value, but the flow valve will remain open only during a predetermined interval and thereafter will close positively, irrespective of the pressures in the tubing or annulus. The cycle will be repeated indefinitely as long as the pressure conditions in the tubing and annulus remain at the value for which the control mechanism is set.

Where a series of these valves are run on a tubing string for the purpose of unloading the well from a high static fluid level to a low operating fluid level, the upper valves should remain closed when a lower valve is in operation. With intermitting or slug type lifting, the upper valves may be subjected to pressures equal to or above the pressure charge in the bellows 129. This increase in pressure will occur during a relatively short interval and, probably, would not let the valve open due to the time delay built into the main valve control.

However, more positive closure of an upper valve can be insured by use of the accumulator chamber or dome, as at 125. Increased pressure in the tubing would tend to force the charge within the bellows through orifice 118, thus delaying contraction of the bellows for a period long enough to allow the increase in tubing pressure, due to the action of a lower lift valve, to subside.

If it is desired to use this valve arrangement as a pilot valve for a larger ported auxiliary or slave valve, the arrangement of FIG. 7 may be utilized. In this form, a slave valve 155 of the resilient sleeve type is secured at its ends 156 and 157, respectively, to the inner and outer walls 158 and 159 of the housing 160 which is secured to the lower extremity of valve actuator housing 161. Housing 161 and the valve and actuator parts therein are the same as in FIGS. and 6, including a flow valve 162 which, in this instance, acts as a pilot valve. Sleeve valve 155 normally is held by radially resilient coiled spring 163 in closing engagement with ports 164 in inner wall 158 so as to prevent the access of annulus fluid into the interior of the tubing. The annulus fluid pressure is supplied through orifices 165 into chamber 166 below the sleeve valve. Under normal conditions, annulus pressure also is supplied through a restricted orifice 167, valve chamber 168, and a passageway 169 into chamber 170 above the sleeve valve. Thus, under normal conditions, pressures on opposite sides of the sleeve valve will be balanced so that spring 163 will maintain this valve closed against ports 164.

Upon opening of pilot valve 162 to initiate the timed cycle, as explained above, tubing pressure will be supplied through passage 171, chamber 168, and passageway 169 to chamber 170, which pressure, being lower than the annulus pressure, will permit the sleeve valve to open for the introduction of annulus fluid through ports 165 and 164 into the interior of the tubing. At the end of the timed interval, the pilot valve will reclose causing closure of main flow valve 155.

Thus, I have provided normally closed tubing flow control means which may open, for instance, responsive to the existence in the tubing of a predetermined pressure head, but which will be positively closed after a predeterminde interval irrespective of pressure conditions in the tubing or annulus. In each form of the invention, there are elements constituting, in effect, a lostmotion operating connection between the flow valve and a prime mover which is motivated by the annulus gas pressure and retarded for timed action by dash pot means. In FIGS. 2-4, the prime mover is the plunger 52, 53 and the elements 61, 62, 64 and 50 form the lost motion connection to the pilot valve which controls the flow valve. In FIGS. 5 and 6, plunger 137 is the prime mover while cage 140 and the headed stem 123 form the lost motion connection. Obviously, since initiation of opening of the flow valve is responsive to conditions within the tubing string, the herein disclosed arrangements are especially useful in connection with multistring wells wherein the pressure conditions in different tubings may vary widely. The control is entirely downwell so that, once set, the devices will continue to function without surface attendance and servicing. The concepts of a separate actuator, as in the first form, is further disclosed and claimed in my co-pending application mentioned above. A principal advantage of such separate actuator is that flow valves, as desired, may be installed in the tubing string, but will remain inoperative until the separate actuator is run. Various types of main fiow valves of the slave type may be herein utilized, also, as disclosed in said co-pending application. Particularly in the forms of FIGS. 57, means other than spring 134 may be provided for returning plungers 133 and 137 independently of tubing pressure. While the present invention finds an important utility in connection with gas lift production of oil wells, it may also find utility in other situations demanding compa- 8 rable control of the fluid flow from the well annulus into tubing. The invention may be modified in various respects as will occur to those skilled in the art and exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. Flow control apparatus for well tubing comprising a tubular housing for connection to the tubing in communication with the interior thereof a flow passage into said housing, valve means normally closing said passage, timing mechanism in said housing, a device in said housing responsive to fluid pressure conditions therein, and means operatively connecting said timing mechanism and said device with said valve means for controlling said passage jointly in accordance with time and tubing pressure.

2. Flow control means for a well having a tubing string comprising a housing for application to the tubing string in communication with the interior thereof, flow passage means in the wall of said housing, valve means controlling said passage means, a plunger in said housing, lost motion means operatively connecting said plunger and said valve means, means for exposing one side of said plunger to fluid pressure externally of said housing for urging said plunger in a direction to actuate said valve means, and dash pot means operatively connected to said plunger for delaying actuation of said valve by said plunger.

3. Means to control the flow of fluid from a well annulus into a tubing string in a well comprising a housing for insertion in the string, a flow passage through the wall of said housing, a valve controlling said passage, first and second chambers in said housing, a restricted orifice connecting said chambers, a plunger in said first chamber, an operative connection bet-ween said valve and said plunger, one face of said plunger communicating with the well annulus for causing actuation of said plunger and said valve in one direction responsive to annulus fluid pressure, a fluid charge in said first chamber and applied to the opposite face of said plunger for transfer through said orifice to retard plunger actuation in said direction, and means for reversing the actuation of said plunger and said valve at the end of the plunger stroke in said direction.

4. Flow control means as described in claim 3 in which said first chamber communicates with said flow passage on the annulus side of said valve, the movement of said plunger by annulus pressure applied to said first mentioned face causing opening of said valve to interconnect the interior of the tubing string with said first chamber and thereby cause reduction of the pressure in said first chamber and reversal of said plunger and recl-osi-ng of said valve.

5. Flow control means as described in claim 3 in which said plunger reversing means comprises a spring calibrated to yield under the influence of predetermined fluid pressure in the well annulus.

16. Flow control means as described in claim 5 further including a movable wall traversing said second chamber and exposed on one face to said fluid charge, and duct means connecting said second chamber on the opposite side of said movable wall with the interior of the tubing string whereby the annulus fluid pressure must exceed the tubing pressure in order to cause v a'lve opening actuation of said plunger.

7. Gas lift flow control means as described in claim 3 further including snap action means momentarily resisting opening of said valve.

8. Gas lift flow control means as described in claim 3 in which said operative connection comprises a lost inotion operative connection between said valve and said plunger and further includes an over center spring device for resisting actuation of said valve during portions of the movement of said plunger.

9. Gas lift intermittent flow control means for a cased oil Well having a tubing string extending to a production zone comprising a housing connected in the tubing string, a flow passage through the wall of said housing, .a valve controlling said passage, a first chamber in said housing communicating with said passage upstream of said valve, a plunger in said chamber, a lost motion operative connection between said valve and said plunger for opening said valve responsive to movement of said plunger by pressured lifting gas from the well annulus to thereby connect the interior of the tubing string to said chamber and said annulus, a second chamber in said housing communicating with said first chamber through a restricted orifice, a liquid charge in the portions of said chambers connected by said orifice for transferring movement of said plunger to said movable Wall and for retarding movement of said plunger, and resilient means bearing against said movable wall for shifting said movable Wall and said plunger in the opposite direction upon opening of said valve to reduce the pressure in said first chamber.

10. Gas lift flow control means as described in claim 9 further including resilient stop means projecting in the path of said movable wall for preventing opening of said valve, and said stop means including means for utilizing the tubing pressure to actuate said stop means and being calibrated to prevent opening of said valve until at least a predetermined pressure exists in said tubing.

*11. Gas lift control means as described in claim 10 in which said stop means includes an expan'sible and contractible fluid charged chamber device, and further including calibrated dash pot means communicating with said chamber device for delaying response of said stop means to tubing pressure change.

12. Gas lift apparatus for a well having production tubing, casing, and an annulus therebetween comprising a housing for connection to the well tubing in communication with the tubing interior, a flow passage through the wall of said housing, valve means controlling said passage, a device in said housing actuable responsive to predetermined fluid pressure in said hou sing and tubing, means operatively connecting said device and said valve means for actuating said valve means to open said passage upon the development of said predetermined pressure in said housing, .a plunger in said housing actua-b'le between first 'and second positions responsive to annulus pressure admitted to said housing through said passage, timing means operatively connected .to said plunger whereby motion of said plunger between said positions occurs during a timed interval operative connection between said plunger and said valve means for closing said valve means as said plunger approaches said second position, and means .for returning said plunger to said first position upon closing of said valve means.

13. Gas lift apparatus as described in claim 12 in which said valve means includes a pilot valve operatively connected to said plunger and a slave valve actuable "by said pilot valve and controlling said flow passage.

14. Gas lift apparatus as described in claim 12 in which the operative connection between said valve means and said plunger comprises lost motion connection means and further includes means yieldingly retarding the closing of said valve means to insure a full, timed stroke of said plunger each time said flow valve is opened.

15. Gas lift apparatus as described in claim 14 turther including latch means cooperable with the lost motion connection means between said valve means and said plunger for holding said valve means closed throughout the return movement of said plunger from said second position to said first position, said plunger incorporating means for disengaging said latch means therefrom as said plunger approaches said first position.

References Cited by the Examiner UNITED STATES PATENTS 3,016,844 1/62 Vincent 103--232 LAURENCE V. EFNER, Primary Examiner. 

1. FLOW CONTROL APPARATUS FOR WELL TUBING COMPRISING A TUBULAR HOUSING FOR CONNECTION TO THE TUBING IN COMMUNICATION WITH THE INTERIOR THEREOF A FLOW PASSAGE INTO SAID HOUSING, VALVE MEANS NORMALLY CLOSING SAID PASSAGE, TIMING MECHANISM IN SAID HOUSING, A DEVICE IN SAID HOUSING RESPONSIVE TO FLUID PRESSURE CONDITIONS THEREIN, AND MEANS OPERATIVELY CONNECTING SAID TIMING MECHANISM AND SAID DEVICE WITH SAID VALVE MEANS FOR CONTROLLING SAID PASSAGE JOINTLY IN ACCORDANCE WITH TIME AND TUBING PRESSURE. 